The beautiful young woman whose throat was slit by the sadist who raped her two years ago might still be alive if Brooklyn prosecutors had done their jobs, it was revealed yesterday.

District Attorney Charles Hynes’ office was scrambling to explain yesterday why a judge never got the information that Hemant Megnath – free on a measly $5,000 cash bail – had threatened to kill Natasha Ramen if she testified that he raped her in May 2005.

Had the judge known, he could have thrown Megnath back in jail, The Post has learned.

Despite an order of protec tion, Megnath made the fright ening threats to Ramen’s in- laws at their home in Queens on Oct. 20 and 21, after which police ar rested him for aggra vated harassment, the Queens DA’s Office said.

Queens prosecutors notified their counter parts in Brooklyn who were handling the rape case, but presiding Judge John Walsh never got the message.

Hynes’ office even admits it only planned to ask Walsh for an “admonishment” – a legal wag of the finger – not the revocation of Megnath’s bail that would have put him back behind bars before his rape trial started in April.

“Instructions were given to the assistant [district attorney] to apprise Judge Walsh of the defendant’s arrest on harassment charges in Queens,” said Brooklyn DA spokesman Jerry Schmetterer.

“We cannot say for certain that the judge did receive the information.”

Walsh said the DA’s Office never told him about Megnath’s threats, court spokesman David Bookstaver said.

“He was not aware of any harassment. Had he been aware, he would have done something,” Bookstaver said.

Transcripts of Megnath’s pretrial hearings in Brooklyn, reviewed by The Post, back up Walsh – they make no mention of the October arrest in Queens.

Court records show that Assistant Brooklyn DA Caryn Teitelman represented her office on Dec. 18 at the first hearing on the rape charges after the DA was informed about the threats.

Reached at home, Teitelman refused to comment.

Megnath’s harassment charges were eventually dropped when Ramen’s in-laws refused to cooperate with police. Sources said the pair was afraid to talk with authorities because of their immigration status.

“I didn’t think anything bad was going to come out of it,” said father in-law Robin Ramen.

“I wish I would have taken this thing more seriously. I thought if I leave it alone he wouldn’t bother [his family], but I guess it was the opposite way.”

Even as she lay dying, Ramen used her own blood, pouring from her neck, and her index finger to scrawl some kind of message on the back door of her Queens home, a relative said yesterday. Investigators have been unable to decipher the bloody marks.

After butchering the key witness against him, Megnath, 29, even sent a text message to Ramen’s husband, gloating over what he’d done, the victim’s relatives said.